Valve spring length question...

I took apart a long-ago modified cylinder head and found nicely shaped/lightened rocker arms and aftermarket valve spring parts.
I measured the 3-part valve springs and found the inner and outer spring length is considerably longer than the factory spec.

What considerations do I need to look at when re-assembling the head?
Cam type will be standard Commando. Standard type pistons.

Personally, I would ditch all the race type springs and go with stock springs if the cam is also to be stock. Last thing I would want to do is over-spring a stock cam, asking for trouble with no possible benefit IMHO. HTH
Cheers, Martin

The after market alloy retainer show could get trouble depending on its age and the quality of the part an stress it may have been under. They are known to fail by allowing the valve retaining collets to pull through the center or braking around the thinner shoulder of the outer spring seating area.
I have replaced the ones I found in my head with quality titanium ones but if you use standard cam an stick to normal road RPM limits then standard springs an steel retainers will work fine.

sportsroof said:

Personally, I would ditch all the race type springs and go with stock springs if the cam is also to be stock. Last thing I would want to do is over-spring a stock cam, asking for trouble with no possible benefit IMHO. HTH
Cheers, Martin

Click to expand...

I'll second this....I once rounded off a camshaft (not a Norton) by over-springing it. Only took a few days running to do so.

Slick